Explosives Used To Remove Weir From Dartmoor River - October 2011

Salmon and sea trout can migrate more easily up the River Taw thanks to a ‘Dam Buster’ operation carried out by the Environment Agency and West Country Rivers Trust. The weir near the Dartmoor village of Belstone was a serious obstruction to fish trying to spawn on the headwaters of the Taw. Dating from the 1960’s, the structure at Taw Marsh was part of an old abstraction point once used by South West Water. Normal dismantling methods were ruled out because of the remote location and difficulty getting heavy plant and equipment to the site. The weir was also situated within a Site of Special Scientific Interest (SSSI) containing rare mosses and lichens that could be easily damaged. Before work could start the Environment Agency had to obtain the permission of South West Water, the Duchy of Cornwall, Natural England, Dartmoor National Park Authority and the Belstone Commoners.

On the day of reckoning, a 250 metre exclusion zone was established around the site and specialist contractors brought in to remove the weir in a controlled explosion. ‘The operation was a success and it will now be much easier for fish to reach some pristine spawning grounds high on the Moor. We’ve previously used explosives to prepare sites prior to construction, but this was the first time we’ve used them to demolish a structure. We had to be careful we didn’t damage an old gauging station located nearby,’ said Bob Collett for the Environment Agency. Under the European Water Framework Directive, rivers are required to meet a standard known as ‘Good Ecological Status’. The upper Taw has been identified as falling short of this standard. The removal of the weir at Belstone is just one of several improvements to improve access for fish and help the upper Taw achieve ‘Good Ecological Status.’ The Agency had earlier moved boulders from around its gauging weir at Sticklepath to create a deeper downstream pool making it easier for salmon and sea trout to migrate upstream.

This work was carried out by the Agency’s Operations Delivery staff. Plans are also underway to improve a weir that serves as a water intake for Finches Foundry in Sticklepath. In a joint project with the West Country Rivers Trust, the Agency is seeking to carry out work next spring to reduce the height of the weir to help fish reach their spawning grounds.

Some before and after photos of the weir at Belstone are available from the Environment Agency’s regional press office on 01392 442008.